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Forming, Confining, and Observing Microtubule-Based Active Nematics
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Published on: January 13, 2023

Topological defects in spherical nematics.

Homin Shin1, Mark J Bowick, Xiangjun Xing

  • 1Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA.

Physical Review Letters
|September 4, 2008
PubMed
Summary
This summary is machine-generated.

We investigated topological defects in nematic fluids on a sphere. Elastic anisotropy controls defect arrangement, offering tunable global geometry by adjusting splay and bend moduli.

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Area of Science:

  • Soft matter physics
  • Liquid crystal theory
  • Geometric topology

Background:

  • Topological defects are crucial in condensed matter systems.
  • Their organization in confined geometries, like spheres, is complex.
  • Understanding defect behavior informs material properties and phase transitions.

Purpose of the Study:

  • To investigate the organization of topological defects in nematogens confined to a 2D sphere (S2).
  • To explore the influence of elastic anisotropy on defect arrangement.
  • To determine if defect geometry is controllable via material properties.

Main Methods:

  • Monte Carlo simulations of hard rods (spherocylinders) on the tangent plane of S2.
  • Adiabatic compression to a jammed nematic state.
  • Development and analysis of a lattice nematic model on S2 with tunable elastic constants.

Main Results:

  • A jammed nematic state with four +1/2 disclinations on a great circle was observed.
  • High elastic anisotropy (soft splay K1, stiff bend K3) drives this arrangement.
  • A one-parameter family of degenerate ground states was found in the splay-dominated limit.

Conclusions:

  • The global geometry of topological defects is controllable by tuning the relative splay to bend modulus.
  • Elastic anisotropy is a key factor dictating defect organization in confined nematic systems.
  • This work provides a framework for designing materials with specific defect structures.